Gas turbine trucks (jet air on the road)

Monday, May 15, 2017

Over half a century ago, a number of big manufacturers experimented with alternative power units for heavy trucks in an attempt to make them more powerful, efficient, cleaner and durable. Some ideas disappeared as quickly as they materialised, but others showed potential.

Gas turbine engines were such a phenomenon and raised a few eyebrows in the 70s and 80s. After World War II several well-known manufacturers in both Europe and the USA started their quest to see if it was possible to fit gas turbines instead of diesel engines in heavy road-going vehicles. By 1950 the Boeing Airplane Company unveiled the world’s first gas turbine unit mounted in a truck.The Boeing engine weighed only 90 kgs but developed a good 175hp and was mounted in a 10-tonne Kenworth truck chassis.The tiny looking turbine engine could burn kerosene, diesel oil or gasoline.

The turbine powered Macks were shipped in 1982 to Europe for a sales promotion tour. To comply with European legislation the US trucks were put on British registration plates and fitted out with a tachograph.

Ford’s turbine operations go back to 1955 when a 150hp prototype engine was fitted to a car. A year later this gas turbine unit was tested in a medium-duty Ford C-1100 truck chassis. By 1964 a series of turbine engines from 300 to 600hp had been developed by Ford. The most powerful version was designated the Model 705, and appeared in 1964 in an experimental super truck nicknamed ‘Big Red’. This giant twin-trailer rig was shod with super-single tyres all around, and could haul a payload of 54 tonnes. Its futuristic styling resembled a vehicle from the popular Thunderbirds science fiction TV series.

The 560hp twin turbine engine was matched to a 5-speed Allison Torqmatic transmission that drove both rear axles. The unique truck was run under full load cruising down the US highways at 112 km/h, and was seen regularly for a number of years. Ford claimed that it achieved a fuel consumption of 3.72 miles per imperial gallon.

This White-cabbed Autocar was fitted with a gas turbine made by Orenda Engines in 1966-67.

In 1968, at the International Commercial Motor Show in London, Ford’s British arm showed a 375hp turbine truck based on a US-built Ford W-1000 chassis. The engine, with the code name Model 707, came close to being introduced as a commercially viable power unit.

General Motors was also active in the 1960s in this field. The aerodynamically designed gas turbine ‘Bison’ was an experimental freight carrier conceived by GM’s famous styling section in 1964. Another ‘truck of tomorrow’ from GM appeared in 1965 as the Chevrolet Turbo Titan III. This futuristic fibreglass-cabbed tractor was powered by a GT309 gas turbine engine developing 280hp.

The extensively tested gas turbine was smaller and about one-third lighter than a comparably powered diesel engine. In-cab luxuries included ‘astronaut seats’ and a four-speaker FM stereo radio, and a twoway radiotelephone. The Titan was equipped with a 16-tonne Hendrickson Extended Leaf Tandem Suspension. Again, this radically styled truck never reached production, although GM’s Detroit Diesel division did go on with the development of gas turbines for industrial use.

In 1950 Boeing in conjunction with Kenworthshowed the world’s first truck with a gas turbine engine.

In 1968, some time after the International Harvester Company had taken over gas turbine and aerospace products manufacturer Solar Aircraft, the International Turbostar highway truck appeared. This big tandem axle tractor based on a Transtar COE was powered by a 300hp Solar ‘B’ gas turbine. The same ‘jet engine’ was also fitted to large Lectra Haul ore dump trucks. And in 1962 no less than four Solar 10MC gas turbines, with a combined output of 4800hp, propelled the giant Overland Train MK-II that LeTourneau built for the US Army Corps. The behemoth with a height of 6.2 metres and riding on 54 oversized wheels could haul a load of 150 tonnes and grossed a staggering 421 tonnes!

Autocar also joined the alternative power family in 1966-67 with the introduction of a tandem axle chassis with a 600hp Orenda (a division of Hawker Siddeley) OT-4 gas turbine engine fitted under a White sleeper cab.

In Europe prototype turbine trucks were constructed by, among others, Fiat, Leyland, Magirus and MAN. Around 1968-70 British Leyland came the closest of this group to producing these chassis in series. Records show they built six tandem-drive Leyland Gas Turbine Trucks with facelifted Ergomatic cabs and a 350/400hp turbine engines. Around 1968-70 in Europe, British Leyland built six of these goodlooking tractors with a 400hp gas turbine engine.

Another European manufacturer that was active in this field was Klöckner-Humboldt-Deutz AG of Germany. They had sought contact with US aerospace manufacturer Garrett in the late 1960s. The Garrett Turbine Engine Co. of Phoenix, Arizona, had been quite successful in producing alternative power units. Their first Model 43-44 gas turbine engine had appeared in 1946. Ten years later the range included power units for industrial applications from 30 to 850hp. In 1972, Industrial Turbines International (ITI) was set up, a joint venture between Garrett AiResearch, Mack Trucks, and aforementioned Klöckner-Humboldt-Deutz, to develop and build gas turbine engines from 450 to 650hp. These power plants were specifically meant for fitment in heavy commercial vehicles.

The Model GT601 was a 550hp air-cooled gas turbine engine that was said to be lighter, more reliable, and fuel efficient than a comparable diesel engine. In the 1970s several units were produced and hence extensively tested in road-going vehicles. The first Mack equipped with a GT601 turbine appeared in 1979. It was fitted in a West Coast-built model R-795-S conventional tractor with tandem drive bogie. It was tested on the road until 1980.

Following that a Mack Cruise-Liner (WS-760LST) and a Super-Liner (RWS-760LST), produced at the Hayward California plant, also received Garrett GT601 turbine engines. With its ‘Turbine Power’ badge signifying this was no ordinary Cruise-Liner, only a subdued whine came from under its cab, as it did from under the bonnet of the Super-Liner. The story goes that the exhaust fumes from the huge stacks were so hot that it burned the leaves from the trees! The 540hp gas turbine was coupled to a standard Mack 5x3 Maxitorque transmission.

Driving off in top gear was no problem for the turbine engine, but this did result in higher fuel consumption. The Macks were, according to the test drivers, very easy and comfortable on the road, with no shuddering or vibration in the drive line at all. When accelerating up to full speed the turbine blades were turning at 37,000 rpm, making a sound that is familiar to a jet plane starting.

The Garrett engine could run on diesel oil, kerosene or alcohol. To promote the new concept, the two Macks were shipped to Europe in 1982 for a tour through the UK, Benelux (Belgium, Netherlands, Luxembourg) and Germany. Once back on home ground, the one-of-a-kind Bulldogs were tested on US highways until 1986. By then the Garrett/Mack/KHD consortium came to a conclusion, as the much-improved diesel engine could not be beaten on price or economics, not to mention compliance hurdles in North America and Europe.

Honours for the biggest turbine powered truck go to LeTourneau’s Overland Train MK-II of 1962 that offered a combined power of4800hp!